Roof drain, motor side, is this how it works?

T

TonyP

Active member
 Dorset
I've been trying to understand how the drainage works on the motor side of an E85, the other side is simple, visible tube at the top which runs straight down to the ahem one way valve, or bung as we like to call it.

The roof motor side is less obvious, so have been reading up a bit, I've knocked up a simple diagram, ignore the scaling, but in principle is this right?, I've drawn it for how it is on the facelift, which as I understand it the motor sits in an additional 'bucket' ,so does this secondary bucket have a drain of its own?, or is it a case of if water gets in it's never going to get out?

 
Almost right - the new plastic housing (called, and containing, sound insulation) completely encloses the facelift roof motor. Saying that, I'm not 100% sure it's a facelift thing, or a revised spare part... But I read somewhere recently that the pre-facelifts did not have a housing at all, just the sound insulation around the motor.

The BMW fix when replacing the motor includes drilling the top drain holes larger, and removing the rubber bungs at the bottoms of the drains.
 
Thanks Bing, so more like this?:-



Is there a drain tube at the top or is it a one-piece moulding that includes the lower bucket?

Interesting what you said re the bungs, I googled around to find out whether to leave them off or not, one person somewhere said that leaving it off had caused water ingress into the boot, something about the spray being sucked upwards, bungs refitted & no further issues.

In my opinion, with the bung in place there is a ridge at the top of it inside the tube which would cause a restriction & make it easier for things to collect there & eventually block.

Is there any official BMW documentation around re enlarging the drain hole & leaving bungs off?
 
It's two piece - a bucket that holds the motor and then a smaller lid that clips on - the hydraulic lines go out the side where the two join. So it's not sealed. Some have sealed it with silicone - my indie said it wasn't required if the drains are working as they do should after modification. Others have drilled drain holes in the bottom of the housing - something I wouldn't do because if the drains get blocked again then it will just fill up faster.

As for the bungs, mine were taken out in October 2012 on my last car - daily driver, no issues with water ingress. Not sure how this can happen as the exit point is behind the wheel arch trim and protected from the elements. For water to get into the boot from there it would have to be sucked up a foot or more of drain, and I don't know where the suction to do that would come from ? Also, that area is physically quite separate to the boot. Water ingress in the boot is most commonly associated with leakage through the rear light housings I think.

The only issue with removing the bungs is possible increase in road noise, but tbh I didn't notice any difference - it's a noisy cabin anyway... And the roof is down as much as it's up anyway :driving:
 
Mind made up, bungs out it is :thumbsup:

Just off to father-in-laws who has an air line - going to blow out the motor side, I've already done the other easy side by poking a bit of wire down & had left the bung off on that one already.

Thanks for your help with this, I understand it all much better now.

Tony
 
I left my bungs in... But have poked a bit of pipe cleaner up there once a year... Lucky mine been fine, and it spend most its time outdoors.


Sent from my iPhone 5s using Tapatalk
 
Ive had mine cleared out but would like pictures as well as im also simple. A video could be great if someone would be kind enough to quickly do one.
 
Is it possible to get to the drain pipes from the top? As soon as you lower the roof it blocks any sort of access.
I was thinking of taking the rear shelf out and having a look from there (obviously with the roof up).
 
I thought if it's possible make another drain or littles holes on the bodyworks near the main drain.

R3AP4R said:
Is there a how 2 on this? The only one I've found the pics have gone! I'm a simple man, I need pics!
Click to expand...

http://www.zpost.com/forums/showthread.php?t=63033
 
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